Problem: Expand. If necessary, combine like terms. $(2x+5)(2x-5)=$
Explanation: Notice that this expression has the following special form: $(a+b)(a-b)$ This form expands to what we call "a difference of squares": $( a+ b)( a- b)= a^2- b^2$ Using the above pattern, we get: $\begin{aligned} ({2x}+ 5)({2x}- 5)&=({2x})^2- 5^2 \\\\ &=4x^2-25 \end{aligned}$